I disagree, something to throw on at the belay is better than nothing! Most 100g of more primaloft fill jackets weigh upwards of 600g and are too heavy, bulky to hang of harness. No one likes leading hard pitches wearing a sack, seconding is not as bad, though can still be a pain and awkward.

These pieces weigh sub 400g, pack small enough to hang of gear loop. Last season I purchased a ME Compressor for this very reason, 2 way zip, helmet compatable hood.

> have to disagree with it being a bely jacket (maybe for summer alpine adventures) but i find it suites more as a mid layer for winter use.

As long as you stay absolutely still or like to boil in a bag. Rab Strata much more comfortable as a midlayer. I would use the Xenon as a lightweight packable and portable (on harness) piece. Warmth to weight performance is phenomenal. Perhaps ideal for lightweight Alps as you say, but great for UK 3½ seasons too, especially multipitch.

I still prefer my old photon hoody as a many of the features you consider positive (the lack of Velcro tab cuffs and the style of the hood without adjustability) are in my opinion a step backwards. Also, I run a bit cold so prefer the heavier 100g per m2 insulation in the body.

Certainly gets a thumbs up from me - its lightness and 'packability' allows it to be easily carried on routes clipped to harness and quickly put on on belays. Its lighter than a lot of fleeces and loads warmer and wind proof. Ive hardly worn a fleece since Ive had this jacket. Havent used as a winter belay jacket so far. Poss hood would benefit from small adjuster (the only slight gripe)